JP2019206014A - Double blank detector for press machine and metal mold protector for press machine - Google Patents

Abstract

To provide a double blank detector for a press machine which can reliably detect a double blank when the double blank is supplied to the press machine, and a metal mold protector for the press machine.SOLUTION: A double blank detector 302 for a press machine which uses a press machine equipped with a die cushion device and automatically repeatedly forms blank materials one by one. The double blank detector 302 comprises: a position signal acquisition part 320 which acquires a slide position signal which indicates a slide position of the press machine; a load signal acquisition part 310 which acquires a die cushion load signal which indicates a die cushion load which is generated in a cushion pad of the die cushion device; and a double blank detection part 330 which detects the state where the plural blank materials are overlapped, as a double blank, on the basis of the slide position signal acquired by the position signal acquisition part 320 and the die cushion load signal acquired by the load signal acquisition part 310.SELECTED DRAWING: Figure 13

Description

  The present invention relates to a double blank detection device for a press machine and a mold protection device for the press machine, and more particularly to a technique for reliably detecting a double blank (two blanks) supplied to the press machine.

  Conventionally, as a method for detecting this type of double blank, there is one described in Patent Document 1.

  The die protection device for a direct-acting press described in Patent Document 1 is used when a blank material (workpiece) is formed using a direct-acting press machine in which a hydraulic cylinder that moves a slide up and down is driven by a servo valve. The slide position is detected when the press load signal rises suddenly (calculated from the hydraulic cylinder descending pressure signal and the ascending pressure signal) at the start of molding, and the detected slide position is within the plate thickness tolerance range (one sheet When it is outside the allowable thickness range set based on the reference thickness position with respect to the workpiece, it is determined that a double blank has occurred, and the slide is moved in the opposite direction to that during pressure processing. Note that the direct acting press described in Patent Document 1 does not include a die cushion device.

JP 10-193199 A

  The double blank detection method described in Patent Document 1 detects the press load and slide position, detects the slide position where the press load suddenly rises at the start of molding, and the detected slide position is outside the allowable thickness range. In some cases, it is determined that a double blank has occurred. However, since the double blank is detected based on the slide position where the press load suddenly rises (that is, the slide position detected based on the press load), there are the following drawbacks. .

  The first disadvantage of using the press load is that the press load signal indicating the press load becomes complicated (defect A) because the press load is the sum of the die cushion load and the molding load.

  This makes it easy to change the molding element due to individual differences (thickness, hardness, and other characteristics) of the material, and the timing at which the press load suddenly rises even during normal operation fluctuates, detecting abnormalities (double blanks). It becomes difficult to do.

  The second disadvantage of using the press load is that the press load is larger and longer than the die cushion device with respect to the die cushion load (the frame of the press machine is easy to expand and contract), and generally has a natural frequency. This is a point (defect B) that is easily affected by natural vibrations (excited by a press load acting shockfully at the start of the press load action).

  When a natural vibration component is included in the press load signal, it is difficult to detect abnormality (double blank).

  The third drawback of using the press load is the point that the resolution of the press load signal is rough (defect C). The ratio between the press (maximum allowable) load and the die cushion (maximum) load of a press machine provided with a die cushion device is generally in the range of 3: 1 to 6: 1. If the same load detector is used for press load detection and die cushion load detection, the resolution of the press load signal is at least 1/3 of that of the die cushion load signal. Abnormality (double blank) detection accuracy decreases.

  The present invention has been made in view of such circumstances, and when a double blank is supplied to the press machine, the double blank detection device of the press machine and the mold protection of the press machine that can reliably detect this. An object is to provide an apparatus.

  In order to achieve the above object, according to one aspect of the present invention, there is provided a double blank detection device for a press machine that uses a press machine with a die cushion device and automatically and repeatedly forms a blank material one by one. A position signal acquisition unit that acquires a slide position signal indicating a slide position of a press machine, a load signal acquisition unit that acquires a die cushion load signal indicating a die cushion load generated in a cushion pad of the die cushion device, and the position A double blank detecting unit that detects a state in which a plurality of the blank materials are overlapped as a double blank based on the slide position signal acquired by the signal acquiring unit and the die cushion load signal acquired by the load signal acquiring unit.

  According to one aspect of the present invention, instead of detecting the press load described in Patent Document 1, the die cushion load is detected, and the slide position signal indicating the slide position and the die cushion load signal indicating the die cushion load are detected. Based on this, a double blank is detected.

  The die cushion load signal is simpler than the press load signal that is the sum of the die cushion load and the molding load, and the die cushion load signal is highly stable against a sudden rise of the die cushion load. Further, the press machine is heavier and longer than the die cushion device, and the natural frequency excited by the press load acting impactively at the start of the press load action is smaller in the press machine than in the die cushion device. The press load signal is easily affected by the natural vibration because the natural frequency of the press machine is smaller than the natural frequency of the die cushion device. Conversely, the die cushion load signal is less susceptible to natural vibration than the press load signal. Further, when the same load detector is used, the resolution of the die cushion load signal is higher than the resolution of the press load signal because the die cushion load is smaller than the press load.

  The slide position signal at the time of rising of the die cushion load signal has a strong tendency to show a constant value during normal (production without abnormality). This is because the die cushion device exhibits one spring characteristic (at least at the time of starting the die cushion load action, inherent elasticity), and its force and position (displacement) are substantially proportional. Further, the die cushion load signal has high responsiveness and detection accuracy. By taking advantage of this feature, when the thickness of the material changes (two or more sheets overlap), a double blank can be obtained from the change in the slide position when a constant (relatively small) die cushion load starts to occur. Can be detected quickly (immediately after the start of molding) and reliably (without omission of detection).

  In the double blank detection device according to another aspect of the present invention, the double blank detection unit holds the slide position signal when the die cushion load signal rises to a predetermined value, and the held slide position signal hold value. It is preferable to detect the double blank when the held slide position signal hold value is equal to or greater than the abnormality identification value. When normal, the slide position signal hold value at the time of rising to a constant (predetermined value) die cushion load signal is stable, so abnormalities (double blanks) are reliably detected from fluctuations of the slide position signal hold value over the abnormal identification value. Can be detected.

In the double blank detection device according to still another aspect of the present invention, the abnormality identification value is Y, the average value of the slide position signal hold value obtained by repeating the molding of one blank material a plurality of times is X _AVE , When the thickness of the blank material is T, the abnormality identification value Y is as follows:
Y ≧ (XAVE + 0.3T), and _{Y <(X} AVE + T)
Is preferably set to a value that satisfies the above.

The slide position signal hold value at the time when the die cushion load signal rises to a predetermined value is a slide position that is higher by one blank than the normal state when double blank is detected. That is, the slide position signal hold value is larger than the average value _XAVE .

Therefore, the abnormality identification value Y is set within the range of the value obtained by adding the average value of the slide position signal hold value to X _AVE and the fluctuation amount (30% to less than 100% of the blank thickness T), and the slide position By detecting a case where the signal hold value is equal to or greater than the abnormality identification value Y as a double blank, a double blank (two or more blank materials) can be reliably detected.

In the double blank detection device according to still another aspect of the present invention, the abnormality identification value is Y, and the slide position signal hold value obtained when a two-layer blank material is tried is X ′, and the blank material plate When the thickness is T, the abnormality identification value Y is as follows:
Y <X ′ and Y ≧ (X′−0.7T)
Is preferably set to a value that satisfies the above.

  Abnormality within the range of values obtained by subtracting the amount of variation (greater than 0% of the blank thickness T and less than 70%) from the slide position signal hold value X 'obtained when trying two blanks. By setting the identification value Y and detecting the case where the slide position signal hold value is equal to or greater than the abnormality identification value Y as a double blank, the double blank can be reliably detected.

  The double blank detection device according to still another aspect of the present invention preferably includes a first manual setting device for manually setting the abnormality identification value or a first automatic setting device for automatically calculating and setting.

  In the double blank detection device according to still another aspect of the present invention, the predetermined value of the die cushion load signal may be a value within a range of 5% to 20% of the maximum die cushion load of the die cushion device. preferable.

  The predetermined value of the die cushion load signal is within the range of 5% or more and 20% or less of the maximum die cushion load in order to detect the change of the die cushion load signal reliably and to detect double blanks at the earliest possible stage. It is desirable that

  In the double blank detection device according to still another aspect of the present invention, a second manual setting device for manually setting a predetermined value of the die cushion load signal, or an automatic calculation based on a maximum die cushion load of the die cushion device It is preferable to have a second automatic setting device for setting.

  In the double blank detection device according to still another aspect of the present invention, a slide position detector that detects a slide position of the press machine and outputs the slide position signal, and a die cushion load generated in the cushion pad are detected. And a die cushion load detector that outputs the die cushion load signal, the position signal acquisition unit acquires the slide position signal from the slide position detector, and the load signal acquisition unit includes the die cushion load detector. The die cushion load signal is preferably acquired from a cushion load detector.

  The slide position signal and die cushion load signal can be obtained from the press machine and die cushion device, respectively, and it is not necessary to add a dedicated detector to detect these signals. Can do.

  A mold protection device for a press machine according to still another aspect of the present invention includes a braking device that brakes a slide driven by a press driving device of the press machine, and a built-in slide that is driven by the press driving device. A hydraulic cylinder that moves a mold mounting surface of the slide relative to the movement of the slide, a double blank detection device of the press machine, and a double blank detection unit. When the double blank is detected, sudden braking of the slide is started by the braking device, and the hydraulic cylinder is depressurized to move a part including the mold mounting surface of the slide relatively in the upward direction. A safety treatment device.

  When the double blank is detected by the double blank detection unit, the braking device starts the sudden braking of the slide. For example, in the case of a press machine driven by a servo motor, sudden braking is applied by applying a maximum torque to the servo motor in the braking direction. Even if the sudden braking is started, due to the inertia of the slide or the like, the slide is stopped for a finite time, and the molding proceeds during that time, thereby increasing the risk of damaging the mold. Therefore, sudden braking is started and the hydraulic cylinder built in the slide is immediately depressurized so that a part including the mold mounting surface of the slide can be relatively moved in the upward direction. Accordingly, the slide (mold) is safely stopped before molding is started, and the mold is prevented from being damaged (mold is protected).

  In the die protecting device for a press machine according to still another aspect of the present invention, the die cushion device supports the cushion pad, raises and lowers the cushion pad, and generates a die cushion load on the cushion pad. A cushion driving unit; a die cushion load commanding device for outputting a die cushion load command; and controlling the die cushion driving unit based on a die cushion load command output from the die cushion load commanding device; A die cushion load controller that generates a die cushion load corresponding to the die cushion load command. When the double blank is detected by the double blank detector, the cushion pad is Of the moving area As long as the slide does not start, a predetermined die cushion load command is output during the period until the slide stops, and the hydraulic cylinder is retracted by the die cushion load generated in the cushion pad in response to the die cushion load command. It is preferable that a part including the mold mounting surface of the slide is relatively moved in the ascending direction.

  The hydraulic cylinder built in the slide is retracted by the contraction action of the hydraulic cylinder by the die cushion load applied from the cushion pad, and a part including the mold mounting surface of the slide rises as the hydraulic cylinder retracts. Move relative to the direction. In addition, a predetermined die cushion load command is output for a period until the slide stops only in an area where molding is not started. On the contrary, the die cushion load is basically not applied in the molding region when the double blank is detected, which is a very dangerous state for the mold.

  In the die protection device for a press machine according to still another aspect of the present invention, the die cushion device includes a die cushion position command device that outputs a die cushion position command, and a die cushion load control by the die cushion load controller. A die cushion position controller that controls the die cushion drive unit based on a die cushion position command that is output from the die cushion position commander later and moves the cushion pad to a predetermined die cushion standby position; Preferably, the predetermined die cushion standby position is a position moved in the upward direction by a predetermined amount from the position where molding is started. This is to ensure a slide stop time (amount of descent of the slide mold mounting surface) until molding is started when a double blank is detected.

  In the die protecting apparatus for a press machine according to still another aspect of the present invention, the region where the molding is not started is a region between the predetermined die cushion standby position and the position where the molding is started.

  In the die protecting apparatus for a press machine according to still another aspect of the present invention, the die cushion load command device is configured to provide a maximum as the predetermined die cushion load command when the double blank is detected by the double blank detection unit. It is preferable to automatically output a die cushion load command.

  This is because when a double blank is detected, the maximum die cushion load is applied to the slide incorporating the hydraulic cylinder, and the hydraulic cylinder is retracted as quickly as possible so that molding is not started.

  According to the present invention, since the die cushion load with high detection accuracy is used for the detection of the double blank, this can be reliably detected when the double blank is supplied to the press machine.

FIG. 1 is a diagram used to explain the detection principle of a double blank in the double blank detection device according to the present invention. FIG. 2 is a waveform diagram showing the die cushion position, the press / slide position, the die cushion load, and the press load for one second including the time from the start of the normal die cushion action process to the middle stage. FIG. 3 is a waveform diagram showing a die cushion position, a press / slide position, a die cushion load, and a press load for one second including the time point from the start of the die cushion action process at the time of abnormality (double blank) to the middle stage. FIG. 4 is an enlarged view of period A (0.04 seconds including the time point when the die cushion action starts) shown in FIG. FIG. 5 is an enlarged view of period A (0.04 seconds including the time point when the die cushion action starts) shown in FIG. FIG. 6 is a diagram showing the principle of initial die cushion load action in an air cylinder drive type die cushion device. FIG. 7 is a schematic configuration diagram illustrating an embodiment of the entire apparatus including a press machine, a die cushion device, and a mold protection device. FIG. 8 is a diagram showing a mechanical portion of the press machine 100 and the die cushion device 200 shown in FIG. FIG. 9 is a configuration diagram illustrating an example of the press driving device 240 illustrated in FIG. 7. FIG. 10 is a configuration diagram illustrating an example of the overload removal device 220 illustrated in FIG. 7. FIG. 11 is a block diagram showing an example of the die cushion drive device 160R shown in FIG. FIG. 12 is a block diagram mainly showing an embodiment of the die cushion controller 170 shown in FIG. FIG. 13 is a block diagram showing an embodiment of the double blank detection device 302. FIG. 14 is a diagram illustrating an example of a mold protection device setting screen. FIG. 15 is a waveform diagram showing a slide position and a die cushion position. FIG. 16 is a waveform diagram showing a predetermined value of the die cushion load signal, a die cushion load command, and a die cushion load. FIG. 17 is a waveform diagram showing the pressure in the head side hydraulic chamber of the hydraulic cylinders 107R and 107L with a built-in slide. FIG. 18 is a waveform diagram showing detection of the slide position signal hold value X, the abnormality identification value Y, and the double blank. FIG. 19 is an enlarged waveform diagram of a part of the waveform diagram shown in FIG. FIG. 20 is an enlarged waveform diagram of a part of the waveform diagram shown in FIG. FIG. 21 is an enlarged waveform diagram showing a part of the waveform diagram shown in FIG. FIG. 22 is a waveform diagram obtained by enlarging a part of the waveform diagram shown in FIG.

  Preferred embodiments of a double blank detection device for a press machine and a mold protection device for a press machine according to the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 is a diagram used to explain the detection principle of a double blank in the double blank detection device according to the present invention.

  The left side of FIG. 1 shows a normal time when one piece of material (blank material) is supplied to the press machine, and the right side of FIG. 1 shows a double blank time (when abnormal) when two pieces of material are supplied to the press machine. Both the left and right sides show the die cushion load action start point at which the die cushion load starts to act from the state shown in FIG.

  In FIG. 1, a press machine 100 is a so-called mechanical servo press in which a slide 110 is driven via a crankshaft and a connecting rod by a servo motor described later, and an upper mold mounted on a mold mounting surface of the slide 110. In this example, a large-sized thin plate material 80 such as automobile body molding is drawn between 120 and a lower mold 122 mounted on the upper surface of the bolster 102.

  The die cushion device 200 presses and holds the periphery of the material 80 formed by the press machine 100 between the upper mold 120 and the blank holder (claw presser plate) 124. The blank holder 124 includes a plurality of cushions. It is held by the cushion pad 128 via the pin 126. In the die cushion device 200, as a driving method for generating a die cushion load (force) on the cushion pad 128, an air cylinder driving method, a hydraulic cylinder driving method using a hydraulic servo valve, and a hydraulic pump / motor axially connected to a servo motor. There are a hydraulic cylinder driving system (Japanese Patent Laid-Open No. 2006-315074) and a screw-nut driving system using a servo motor, etc. Regardless of the driving system, various die cushion devices have one spring characteristic (at least a die At the time of starting the cushion load action, it shows inherent elasticity), and its force and position (displacement) are almost proportional. In FIG. 1, it is shown that there is one spring characteristic regardless of the driving method of the die cushion device 200.

  From the state shown in FIG. 1 (when the slide 110 comes into contact with the cushion pad 128 via the upper mold 120-material 80-blank holder 124-cushion pin 126 and the die cushion load starts to act), When the slide 110 is further lowered, the die cushion load at the initial stage of the die cushion load action is proportional to the slide position (displacement) at which the cushion pad 128 is indirectly pushed down by the slide 110 as shown in the graph of FIG. It occurs in the same way. That is, the slide displacement / initial die cushion load is the same on the left and right. This is because the spring characteristics of the die cushion device 200 are the same.

  On the other hand, the die cushion load starts to act from a slide position that is larger by the plate thickness (T) of the material 80. Therefore, the slide position when the die cushion load becomes a predetermined value (initial die cushion load) is larger on the right side than on the left side by the thickness T of one material.

  Therefore, the present invention detects a double blank from the change in the slide position when the die cushion load rises to a predetermined value, based on the slide position signal indicating the slide position and the die cushion load signal indicating the die cushion load.

[Comparative example]
Fig. 2 shows the starting point of the die cushion action process when a die cushion load is set to 2000 kN using a press machine with a pressurizing capacity of 10000 kN, and one piece of material with a plate thickness of 0.8 mm is processed as if it were normal. FIG. 4 is a waveform diagram (upper waveform diagram) showing a die cushion position and a press / slide position for 1 second including from the middle to the middle plate, and a waveform diagram (lower waveform diagram) showing a die cushion load and a press load.

  FIG. 3 is the same setting as in FIG. 2, and the die cushion position and press / press for 1 second including from the start of the die cushion action process to the middle stage when processing two sheets in the case of abnormality (double blank). FIG. 6 is a waveform diagram showing the slide position (upper waveform diagram) and a waveform diagram showing the die cushion load and press load (lower waveform diagram).

  The press machine is a system that drives a slide through a link mechanism with a servo motor, and the die cushion device is a system that drives a cushion pad through a hydraulic pump / motor and a hydraulic cylinder that are connected to the shaft by a servo motor. is there. In addition, the metal mold | die used with the press machine removes the lower mold | type (punch) for a double blank detection experiment, and material is pressurized only between an upper mold | die (die) and a blank holder.

3 is more than one material (with a thickness of 0.8 mm) as compared to FIG. 2, but there is no difference with respect to the die cushion load action and the like, and it shows almost the same behavior. I understand. (Data is measured at 2 millisecond intervals.)
2 and 3, the reason why the press load is smaller than the die cushion load in the middle stage of the die cushion action process is due to a detection error. This is because the detection accuracy of the press load is inferior to that of the die cushion.

  FIGS. 4 and 5 are enlarged views of period A (0.04 seconds including the start point of the die cushion action) in FIGS. 2 and 3, respectively.

  FIG. 5 clearly shows the influence of pressurizing one material (with a thickness of 0.8 mm) as compared with FIG. The characteristics of the die cushion load (the degree of action) and the die cushion displacement (distance that is indirectly pushed down from the die cushion initial position 80.3 mm to the press / slide) are almost constant, and the die cushion load (action) On the other hand, the press / slide position shows a characteristic of 0.8 mm larger corresponding to the thickness of just one material.

  If this characteristic is used (applied), a double blank can be detected at the start of the die cushion action (initial stage of machining).

  That is, the normal press / slide position when the die cushion load rises to a predetermined value (400 kN in this example) is 79.9 mm (FIG. 4), and the press / slide position at the time of abnormality (double blank) Is 80.7 mm (FIG. 5), and the press / slide position at the time of abnormality is a position 0.8 mm higher than the normal time, which corresponds to the thickness of one material.

  Therefore, the press / slide position at the time when the die cushion load rises to a predetermined value is compared with the abnormality identification value, and a case where the slide position is equal to or greater than the abnormality identification value can be detected as a double blank.

  The greatest reason why the double blank detection device according to the present invention is suitable is that the die cushion load at the start of the action of the die cushion load is used. This is because the die cushion device exhibits one spring characteristic (inherent elasticity) at the start of the die cushion load action, and the force and position (displacement) are substantially proportional. This characteristic does not ask | require the kind of die-cushion apparatus.

  For example, hydraulic cylinder drive system with hydraulic servo valve, hydraulic cylinder drive system with hydraulic pump / motor connected to servo motor, screw nut drive system with servo motor, die cushion load (pressure) command, die cushion load ( "So-called" servo (or NC) die cushion device that drives the servo valve or servo motor based on the pressure) to control the die cushion force, the die cushion load action start point (or the die cushion load action start) At the time prior to the time point), the servo valve or servo motor is driven based on the die cushion start (or standby) position command and the die cushion position, and the cushion pad position is held at the die cushion start (or standby) position. Yes.

  In this state, the die cushion load starts to act while the cushion pad is indirectly pushed down by the slide (via the cushion pin, blank holder, material, upper mold, etc.). The die cushion load at the start of the die cushion load action is proportional to X (die cushion start position command−die cushion position) indicating the die cushion position displacement, as shown in the following equation.

[Equation 1]
F = K × X
F: Initial die cushion load (kN)
K: Spring coefficient (kN / mm) of the die cushion device (specific to)
X: Die cushion start position (command)-Die cushion position (mm)
[Expression 1] shows only the spring coefficient which is a static characteristic excluding the dynamic characteristic in the position (feedback) control. The spring coefficient K corresponds to a position proportional constant (gain) when the die cushion position is (feedback) controlled.

  For example, in an air cylinder drive type die cushion device, a die cushion load proportional to the compressed air pressure is basically applied according to the die cushion stroke. An initial die cushion load proportional to the initial displacement X acts.

  FIG. 6 is a diagram showing the principle of initial die cushion load action in an air cylinder drive type die cushion device. In FIG. 6, the same reference numerals are given to portions common to FIG. 1, and detailed description thereof is omitted.

  In FIG. 6, the air cylinder 202 functions as a die cushion driving unit that supports the cushion pad 128 and generates a die cushion load on the cushion pad 128. An air tank 204 capable of adjusting pressure is connected to the air cylinder 202.

  The left side of FIG. 6 shows the die cushion initial position (0), and the initial die cushion load (acting on the cushion pin 126) is inactive (F = 0). The right side of FIG. 6 shows a state in which the die cushion is slightly displaced (Lmm) from the initial position (0) of the die cushion, and is proportional to the air pressure compressed by the minute displacement L from the initial air pressure (before the die cushion stroke). A load (F = fo) acts. The left-right difference due to the minute displacement L in FIG. 6 is excessively shown for easy understanding.

  In the state on the left side of FIG. 6, the thrust of the air cylinder 202 that is constantly acting is borne by the frame (bolster 102) in association with the action of the elastic member (with a spring coefficient K) that is elastically deformed (Lmm). ing. In the state on the right side of FIG. 6, the cushion pin 126 is indirectly pressed by the slide 110, and the cushion pad 128 is pressed down by a minute amount (Lmm), and this is borne by the action of restoring the elastic deformation of the elastic member. . This is the die cushion load (the portion of the thrust of the air cylinder 202 that is constantly acting is borne by the cushion pin 126).

  After all, the spring coefficient K is unique to each die cushion device (type and ability). That is, if the same type of die cushion device is composed of the same machine element and the same control element, the spring coefficient K is the same.

  On the other hand, the reason why the double blank detection method of Patent Document 1 is not suitable is that the press load signal at the start of the press load action is used. That is, by using the press load signal, as detailed in [Problems to be solved by the invention], defect A (the point where the press load signal becomes complicated) and defect B (easily affected by natural vibration). This is because the defect C (the point where the resolution of the press load signal is rough) occurs.

  Furthermore, the fourth drawback of using the press load signal is that the press load signal is slow in response to the die cushion load signal (defect D).

  Generally, the press load signal is dedicated for monitoring, whereas the die cushion load signal is for die cushion load control, so the response of the press load detector is lower than that of the die cushion load detector. . Since the responsiveness is low, the press load signal tends to fluctuate with respect to the die cushion load signal, and the abnormality (double blank) detection accuracy decreases.

  As shown in FIGS. 4 and 5, the influence of the above-described defects B, C, and D appears in the press load signal with respect to the die cushion load signal. 2 to 5 show experimental results when the lower die (punch) is removed so that no molding force is generated, and thus the influence of the defect A does not appear.

Embodiment of the present invention
FIG. 7 is a schematic configuration diagram illustrating an embodiment of the entire apparatus including a press machine, a die cushion device, and a mold protection device.

  As shown in FIG. 7, the entire apparatus is mainly composed of a press machine 100 and a die cushion apparatus 200, and the press machine 100 includes a press controller 190, an overload removal apparatus 220, and a press drive apparatus 240. Has been.

  The die cushion device 200 mainly includes a cushion pad 128, hydraulic cylinders 130R and 130L, die cushion driving devices 160R and 160L, a die cushion controller 170, and the like.

  In this example, the mold protection device 300 (FIG. 12) of the press machine according to the present invention is configured in the die cushion controller 170, and the double blank detection device 302 is configured in the mold protection device 300. .

[Mechanical part of press machine]
FIG. 8 is a diagram showing a mechanical portion of the press machine 100 and the die cushion device 200 shown in FIG.

  The press machine 100 shown in FIG. 8 includes a crown 10, a bed 20, and a plurality of columns 104 arranged between the crown 10 and the bed 20, and a slide 110 is provided on the column 104. The sliding member 108 is guided so as to be movable in the vertical direction.

  This press machine 100 is a so-called mechanical servo press in which a slide 110 is driven via a crankshaft 112 and a connecting rod 103 by a servo motor, which will be described later. Is formed by drawing.

  The crankshaft 112 is provided with an encoder 115 for detecting the angle and angular velocity of the crankshaft 112 as well as the rotational driving force transmitted from the press drive device 240.

  A pair of left and right hydraulic cylinders (hydraulic cylinders) 107L and 107R is built in (fixed) on the slide 110, and the tip of the connecting rod 103 is rotatably fixed to the piston 105 of the hydraulic cylinders 107L and 107R.

  The hydraulic cylinder 107R shown on the right side in FIG. 8 shows the state where the piston 105 moves to the upper end, and the hydraulic cylinder 107L shown on the left side shows the state where the piston moves to the lower end. Yes.

  The relative position between the tip position of the connecting rod 103 and the mold mounting surface (lower surface) of the slide 110 changes due to the expansion and contraction of the hydraulic cylinders 107L and 107R. That is, the hydraulic cylinders 107L and 107R can move the mold mounting surface of the slide 110 relative to the movement of the slide 110 driven by the crankshaft 112 and the connecting rod 103 by the expansion and contraction of the hydraulic cylinders 107L and 107R. it can.

  In addition, a pair of balancer cylinders 111 that apply an upward force to the slide 110 are disposed between the slide 110 and the crown 10.

  An upper mold 120 is mounted on the mold mounting surface of the slide 110, and a lower mold 122 is mounted on the upper surface of the bolster 102 on the bed 20.

[Mechanical part of die cushion device]
The die cushion device 200 presses the peripheral edge of a material (blank material) 80 formed by the press machine 100 from below, and mainly includes a blank holder (claw presser plate) 124, a cushion pad 128, and a pair of left and right. Hydraulic cylinders 130L and 130R are provided.

  The cushion pad 128 supports the blank holder 124 via a plurality of cushion pins 126.

  The hydraulic cylinders 130 </ b> L and 130 </ b> R function as a die cushion driving unit that supports the cushion pad 128, raises and lowers the cushion pad 128, and generates a die cushion load on the cushion pad 128.

  In the vicinity of the hydraulic cylinders 130L and 130R, die cushion position detectors 133L and 133R for detecting the position of the piston rod in the expansion / contraction direction as the position of the cushion pad 128 in the up-and-down direction (die cushion position) are provided.

  The material 80 is set (contacted) on the upper side of the blank holder 124 by a conveying device (not shown).

  When the upper mold 120 mounted on the mold mounting surface of the slide 110 collides with the cushion pad 128 via the material 80, the blank holder 124, and the cushion pin 126 as the slide 110 moves down, The periphery of the material 80 is pressed and held between the blank holder 124 to which the die cushion load is applied from the hydraulic cylinders 130L and 130R and the upper mold 120, and the upper mold 120 and the lower mold 122 are molded.

  The die cushion device 200 of this example has a maximum die cushion load of 3000 kN, a die cushion load setting value of 2000 kN, and a die cushion stroke of 200 mm. However, 15 mm of the die cushion stroke 200 mm is a non-molding stroke ΔZ from when the upper mold 120 contacts the material 80 to when the material 80 contacts the lower mold 122 (ΔZ = 15 mm). That is, the standby position of the blank holder 124 is set to a position (Z2) larger than the molding start position (position Z1 at which the material 80 contacts the lower mold 122), and the stroke ΔZ (before the molding start where the position of the slide lower surface is larger than Z1). = Z2-Z1) is prevented from starting. In this example, the plate thickness of the material 80 is 0.8 mm.

[Press drive device]
FIG. 9 is a configuration diagram illustrating an example of the press driving device 240 illustrated in FIG. 7.

  The press driving device 240 functions as a driving device and a braking device for the press machine 100 (slide 110). The servo motor 106, the reduction gear 101 that transmits the rotational driving force of the servo motor 106 to the crankshaft 112, and the brake device. 230.

  The servo motor 106 is supplied with drive power corresponding to the torque command signal 197 from the servo amplifier 192, and the servo motor 106 is driven and controlled to have a predetermined (setting) slide speed or crank angular speed. The servo amplifier 192 is supplied with power from a DC power supply 196 with a regenerator. When the press machine 100 (slide 110) is braked, the electric power generated by the drive torque of the servo motor 106 acting in the braking direction. Is regenerated to the AC power supply 174 via the servo amplifier 192 and the DC power supply 196.

  An encoder 114 is attached to the rotation shaft of the servo motor 106, and an encoder signal output from the encoder 114 is converted into a servo motor angular velocity signal 195 by the signal converter 113.

  The brake device 230 includes a brake release electromagnetic valve 235, a brake mechanism 239, and a silencer 237 to which compressed air is supplied from an air pressure source 231 through a pressure reducing valve 233.

  A drive signal is applied to the brake release electromagnetic valve 235 from the press controller 190, and the brake release electromagnetic valve 235 is ON / OFF controlled.

  During normal (operation without abnormality), the brake release solenoid valve 235 of the brake device 230 is turned on to release the brake. When (various) abnormality occurs, the torque command signal 197 in the slide reaction direction is sent to the servo amplifier 192. By applying the brake, the slide 110 is braked, and after the stop (approximately at the same time as the stop), the brake release electromagnetic valve 235 is turned OFF and the brake is applied.

[Overload removal device]
FIG. 10 is a configuration diagram illustrating an example of the overload removal device 220 illustrated in FIG. 7.

  As shown in FIG. 10, the overload removal device 220 includes a hydraulic pump 222 connected to the induction motor 221, an accumulator 223, a check valve 224 disposed on the discharge port side of the hydraulic pump 222, and relief valves 225, 226. , A pressure detector 227, and an electromagnetic (decompression) valve 228.

  The high pressure line in which the pressure detector 227 is disposed is connected to the head side hydraulic chamber 109 of the hydraulic cylinders 107R and 107L built in the slide 110, and the low pressure line connected to the accumulator 223 is the hydraulic cylinder 107R and 107L. It is connected to the rod side hydraulic chamber (FIG. 8).

The head-side hydraulic chamber 109 is normally applied with an initial pressure P0 (about 200 kg / cm ² ), and the hydraulic cylinders 107R and 107L are in a no-load state (no external load is applied to the slide 110). (The state on the right side of FIG. 8).

  When pressurizing the head-side hydraulic chamber 109, the contactor 229 is turned on with the pressure detector 227 confirming the initial pressure P0 with the slide 110 at the top dead center (at least no load state) Then turn off).

  Since the set pressure of the relief valve 225 acting on the discharge port of the hydraulic pump 222 is set slightly larger than the initial pressure P 0, a substantially constant initial pressure P 0 can be controlled regardless of the OFF delay time of the contactor 229.

The head side hydraulic chamber 109 is connected to an accumulator 223 that constitutes a low pressure line corresponding to a tank function via a relief valve 226 and a solenoid valve 228, and an abnormal load is applied to the slide 110 (for example, this In the example, when an abnormal cylinder pressure PU (about 320 kg / cm ² ) corresponding to 22000 kN corresponding to 110% of the maximum allowable load of 20000 kN of the press machine 100 is applied, the relief valve 226 is activated and Is detected by the pressure detector 227, the electromagnetic valve 228 is turned on, and the head side hydraulic chamber 109 is depressurized.

  In this example, the cylinder strokes of the hydraulic cylinders 107R and 107L are 30 mm.

[Die cushion drive unit]
FIG. 11 is a block diagram showing an example of the die cushion drive device 160R shown in FIG.

  The die cushion driving device 160R includes a hydraulic circuit that supplies hydraulic oil to the rod-side hydraulic chamber 130a and the head-side hydraulic chamber 130b of the hydraulic cylinder 130R shown in FIG. 8, and mainly includes an accumulator 162, a hydraulic pump / motor 140, and hydraulic pressure. Servo motor 150 connected to the drive shaft of pump / motor 140, encoder 152 for detecting the angular velocity (servo motor angular velocity ω) of the drive shaft of servo motor 150, relief valve 164, check valve 166, and die cushion load It comprises a pressure detector 132 corresponding to the detector.

  The die cushion drive device 160L that supplies hydraulic oil to the hydraulic cylinder 130L has the same configuration as the die cushion drive device 160R, and therefore the die cushion drive device 160R will be described below.

  The accumulator 162 is set with a low-pressure gas pressure, serves as a tank, and supplies substantially constant low-pressure oil via a check valve 166 to the head-side hydraulic chamber 130b (cushion pressure generating-side pressurizing chamber) of the hydraulic cylinder 130R. It also plays a role of facilitating pressure increase during die cushion load control.

  One port (discharge port) of the hydraulic pump / motor 140 is connected to the head side hydraulic chamber 130b of the hydraulic cylinder 130R, and the other port is connected to the accumulator 162.

  The relief valve 164 operates as an abnormal pressure (when the die cushion load control is impossible and a sudden abnormal pressure occurs), and is provided as a means for preventing damage to the hydraulic equipment. The rod side hydraulic chamber 130a of the hydraulic cylinder 130R is connected to the accumulator 162.

  The pressure detector 132 detects the pressure acting on the head side hydraulic chamber 130b of the hydraulic cylinder 130R, outputs a die cushion pressure signal 171R indicating the detected pressure, and outputs from the encoder 152 attached to the drive shaft of the servo motor 150. The output encoder signal is converted into a servo motor angular velocity signal 175R by the signal converter 153.

  The die cushion drive device 160R outputs a torque command signal 177R input from a later-described die cushion controller 170 to the servo amplifier 172, and the servo amplifier 172 outputs the current amplified based on the torque command signal 177R to the servo motor 150. Then, the hydraulic pump / motor 140 is driven. Thus, the hydraulic cylinder 130R is driven, and die cushion pressure (load) control and die cushion position control are performed.

  Since the die cushion load (force) can be expressed by the product of the pressure in the head side hydraulic chamber of the hydraulic cylinder that supports the cushion pad and the cylinder area, controlling the die cushion load is the head side hydraulic chamber of the hydraulic cylinder. It means to control the pressure.

  The force transmitted from the slide 110 to the hydraulic cylinders 130L and 130R via the cushion pad 128 compresses the head side hydraulic chamber 130b of the hydraulic cylinders 130L and 130R, and generates a die cushion pressure. At the same time, the hydraulic pump / motor 140 is caused to act by the die cushion pressure, and when the rotational shaft torque generated in the hydraulic pump / motor 140 resists the drive torque of the servo motor 150, the servo motor 150 is rotated to generate pressure. Rise is suppressed. After all, the die cushion pressure (die cushion load) is determined according to the driving torque of the servo motor 150.

  The die cushion pressure signal 171R output from the pressure detector 132 and the servo motor angular velocity signal 175R output from the signal converter 153 are used by the die cushion controller 170 to generate a torque command signal 177R.

  The torque command signal 177R is output to the servo amplifier 172, the current amplified based on the torque command signal 177R is output from the servo amplifier 172 to the servo motor 150, and the drive torque generated in the servo motor 150 is supplied to the servo motor 150. The die cushion load control generated from the hydraulic cylinder 130R is performed by rotationally driving the hydraulic pump / motor 140 to which the drive shaft is connected to generate pressure to be applied to the head side hydraulic chamber 130b of the hydraulic cylinder 130R.

  The servo amplifier 172 is supplied with power from a DC power supply 176 with a regenerator, and is driven by a driving force from a hydraulic pump / motor 140 acting as a hydraulic motor when controlling the die cushion load (pressure). The electric power generated by the servo motor 150 is regenerated to the AC power source 174 via the servo amplifier 172 and the DC power source 176.

[Press controller and die cushion controller]
FIG. 12 is a block diagram mainly showing an embodiment of the die cushion controller 170 shown in FIG.

  A die cushion controller 170 shown in FIG. 12 mainly includes a mold protection device 300 according to the present invention in addition to a pressure controller (die cushion load controller) 134 and a position controller (die cushion position controller) 136. It consists of

  The pressure controller 134 includes die cushion pressure signals 171R and 171L, servo motor angular velocity signals 175R and 175L, a crank angle signal 191 and a crank angular velocity signal 193, and a die cushion load switching command (to be described later) from a safety treatment device 305. Switching commands for applying the maximum capacity die cushion load when a double blank is detected are respectively added. The crank angle signal 191 and the crank angular velocity signal 193 are signals indicating the angle and angular velocity of the crankshaft 112 converted by the signal converter 194 that receives the encoder signal output from the encoder 115 attached to the crankshaft 112. It is.

  The pressure controller 134 includes a die cushion pressure command device (die cushion load command device) that outputs a preset die cushion pressure (load) command, and controls the die cushion pressure in accordance with the die cushion pressure command. Cushion pressure signals 171R and 171L are input.

  The pressure controller 134 inputs servo motor angular velocity signals 175R and 175L as angular velocity feedback signals mainly for ensuring dynamic stability in die cushion pressure (load) control and position control, and further determines the crank angular velocity. The crank angular velocity signal 193 shown is input for use in compensation for ensuring pressure control accuracy in die cushion pressure (load) control.

  Further, the pressure controller 134 has a signal converter that converts an input crank angle signal 191 into a slide position signal 303 indicating the position of the slide 110 in order to obtain the start timing of the die cushion function. The die cushion pressure (load) control is started or ended based on the slide position signal 303 converted by the control, and the die cushion pressure (load) command unit in the pressure controller 134 corresponds based on the slide position signal 303. Output die cushion pressure (load) command.

  When controlling the die cushion pressure (load), the pressure controller 134 calculates the torque command calculated using the input die cushion pressure command, the die cushion pressure signals 171R and 171L, the servo motor angular velocity signals 175R and 175L, and the crank angular velocity signal 193. The signals 177R and 177L are output to the die cushion driving devices 160R and 160L via the selector 138.

  Further, when a die cushion load switching command for automatically switching the die cushion load is detected from the safety treatment device 305 when a double blank is detected, the pressure controller 134 is configured to use a maximum pressurizing capacity (in this example, an automobile body molding application). Then, torque command signals 177R and 177L corresponding to a general command for applying a die cushion load of 3000 kN are output.

  On the other hand, die cushion position signals 173R and 173L, servo motor angular velocity signals 175R and 175L, and a crank angle signal 191 are added to the position controller 136, respectively.

  The position controller 136 is configured to include a die cushion position command device, and is hydraulic based on the die cushion position command output from the die cushion position command device after the die cushion pressure (load) control by the pressure controller 134 is completed. The cylinders 130L and 130R are controlled. The die cushion position command device is added with die cushion position signals 173R and 173L for use in generating an initial value in the die cushion position command generation. The die cushion position command device includes a slide 110 (cushion pad 128). After reaching the bottom dead center and completing the die cushion pressure (load) control, a product knockout operation is performed and the cushion pad 128 is placed in the die cushion position (cushion) in order to wait at the predetermined die cushion standby position, which is the initial position. A common position command (die cushion position command) for controlling the position of the pad 128 is output.

  In the case of the die cushion position control state, the position controller 136 includes a common die cushion position command output from the die cushion position commander and die cushion position signals 173R and 173L detected by the die cushion position detectors 133L and 133R, respectively. Based on the above, torque command signals 177R and 177L are generated, and the generated torque command signals 177R and 177L are output to the selector 138. The position controller 136 preferably inputs servo motor angular velocity signals 175R and 175L and controls the position of the cushion pad 128 in the ascending / descending direction based on the servo motor angular velocity signals 175R and 175L in order to ensure dynamic stability in position control. . Furthermore, it is preferable to control the position so that the cushion pad 128 does not indirectly collide with the slide 110 at the time of knockout based on the crank angle signal 191 input.

  The selector 138 selects the torque command signals 177R and 177L input from the pressure controller 134 in the die cushion pressure (load) control state according to the selection command input from the pressure controller 134, and the die cushion drive device In the case of the die cushion position control state, torque command signals 177R and 177L input from the position controller 136 are selected and output to the die cushion driving devices 160R and 160L.

  The die cushion controller 170 outputs the torque command signals 177R and 177L generated as described above to the die cushion driving devices 160R and 160L, and the servo motor 150 via the servo amplifier 172 in the die cushion driving devices 160R and 160L. To control die cushion pressure (load) and die cushion position.

  A crank angle signal 191 and a servo motor angular velocity signal 195 are added to the press controller 190, and the press controller 190 performs a predetermined slide based on the input crank angle signal 191 and the servo motor angular velocity signal 195. A torque command signal 197 is generated so as to be a speed or a crank angular speed, and the generated torque command signal 197 is output to the press drive device 240 (servo amplifier 192). The servo motor angular velocity signal 195 is used as an angular velocity feedback signal for ensuring the dynamic stability of the slide 110.

  Further, the press controller 190 generates a torque command signal 197 that causes the press drive device 240 to exert a maximum torque in the braking direction based on the braking command input from the mold protection device 300, and the brake device 230 (brake A signal for turning ON / OFF the solenoid valve for opening 235) is output.

<Mold protection device>
As shown in FIG. 12, the die cushion controller 170 of this example includes a mold protection device 300.

  The mold protection device 300 is configured in the die cushion controller 170 for the convenience of applying the die cushion load signal 301 and the slide position signal 303. The mold protection device 300 has a mission to quickly identify and process an abnormality and requires a faster calculation processing time. For example, a press controller that covers angle control (position control) of a slide (crankshaft). It is generally faster to configure the controller within the die cushion controller 170 that takes charge of the die cushion load (die cushion pressure) control (force control) than when it is configured within the 190 (faster calculation cycle is required) It is effective. Furthermore, compared to the case where a separate mold protection device is provided, this is effective because the dead time associated with the input / output processing of both signals can be omitted.

  The mold protection device 300 includes a double blank detection device 302 and a safety treatment device 305.

[Double blank detection device 302]
FIG. 13 is a block diagram showing an embodiment of the double blank detection device 302.

  As shown in FIG. 13, the double blank detection device 302 includes a load signal acquisition unit 310, a position signal acquisition unit 320, and a double blank detector 330. The double blank detector 330 further includes a predetermined value setting unit 331, 1 comparator 332, hold circuit 333, second comparator 334, and abnormality identification value setter 335.

  The load signal acquisition unit 310 is a part that acquires a die cushion load signal 301 indicating a die cushion load generated on the cushion pad 128 of the die cushion device 200, and the pressure controller 134 of the die cushion controller 170 receives the die cushion pressure. A die cushion load signal 301 indicating a die cushion load calculated based on the signals 171R and 171L is input from the pressure controller 134. Note that the load signal acquisition unit 310 directly inputs the die cushion pressure signals 171R and 171L, and acquires the die cushion load signal 301 indicating the die cushion load calculated based on the die cushion pressure signals 171R and 171L. May be.

  The position signal acquisition unit 320 is a part that acquires a slide position signal 303 indicating the position of the slide 110 of the press machine 100. From the pressure controller 134 of the die cushion controller 170 (a signal converter in the pressure controller 134, The slide position signal 303 is input from the crank angle signal 191).

  In this example, the encoder 115 provided on the crankshaft 112, the signal converter 194 (FIG. 7), and the signal converter in the pressure controller 134 function as a slide position detector. A slide position detector that detects the position of the slide 110 may be provided between the bed 20 (or the bolster 102) of the press machine 100 and the slide 110.

  The die cushion load signal 301 acquired by the load signal acquisition unit 310 is output to the first comparator 332. A predetermined value F is added from the predetermined value setter 331 to the other input of the first comparator 332, and the first comparator 332 compares these two inputs, and the die cushion load signal 301 is When the predetermined value F is reached, a signal that enables the hold circuit 333 to perform a hold operation is output.

  Here, the predetermined value F set by the predetermined value setter 331 is preferably in the range of 5% to 20% of the maximum die cushion load of the die cushion device 200. In this example, the maximum die cushion load is 3000 kN, and the predetermined value F is set to F = 200 kN (a value corresponding to about 7% of the maximum die cushion load 3000 kN). The predetermined value F is manually set by a manual setting device (second manual setting device) or automatically calculated based on the maximum die cushion load of the die cushion device by an automatic setting device (second automatic setting device). It may be set.

  The slide position signal 303 acquired by the position signal acquisition unit 320 is output to the hold circuit 333.

  The hold circuit 333 receives the slide position signal 303 when the die cushion load signal 301 rises to a predetermined value (F) every cycle (when a signal is input from the first comparator 332) with the start of the die cushion load action. Hold.

  The slide position signal hold value X held by the hold circuit 333 is output to the second comparator 334. An abnormality identification value Y is added from the abnormality identification value setting unit 335 to the other input of the second comparator 334. The second comparator 334 receives the slide position signal hold value X, the abnormality identification value Y, and the like. And the case where the slide position signal hold value X is equal to or greater than the abnormality identification value Y is detected as a state (double blank) in which two (a plurality of) materials 80 overlap.

  FIG. 14 is a diagram illustrating an example of a mold protection device setting screen.

On the mold protection device setting screen, the slide position signal hold value X for each molding (mold, material, die cushion load setting value, press machine speed setting, die height setting and other conditions unique to molding) and the normal ( The average value X _AVE of the slide position signal hold value X that is repeated a plurality of times (when one sheet is molded), the predetermined value F of the die cushion load signal when holding the slide position signal hold value X, and the abnormality identification value (double Blank abnormality identification value) Y is displayed.

In this example, the latest value of the slide position signal hold value is X = 195.21 mm, and the average value is X _AVE = 195.20 mm. The latest value is a value in the latest (final) cycle of the production performed in the past, and is held until immediately before the next die cushion load action start time. The average value X _AVE is an average value of normal (no abnormality) performed a plurality of times (in this example, 100 times) performed in the past.

  In addition, the predetermined value F of the die cushion load signal is F = 200 kN in this example, and the abnormality identification value Y that is the threshold for double blank detection is Y = 195.60 mm in this example. It is always displayed on the mold protection device setting screen (FIG. 14).

The abnormality identification value Y set by the abnormality identification value setting unit 335 is a value obtained by adding half of the plate thickness (0.8 mm) to the average value X _AVE = 195.20 mm of the slide position signal hold value X. (Y = X _AVE +0.5 T = 195.20 + 0.5 × 08 = 195.60, where T is the thickness)

The abnormality identification value Y is set manually by a manual setting device (first manual setting device), or the average value X _AVE of the slide position signal hold value X and the plate thickness by an automatic setting device (first automatic setting device). An automatic calculation based on T may be set.

The abnormality identification value Y set by the abnormality identification value setting unit 335 is not limited to 195.60 mm set as described above, but is a slide position signal hold value X obtained by repeating molding of one blank material a plurality of times. _Assuming that the average value X _AVE and the thickness T of the blank material,
[Equation 2]
Y ≧ (X _AVE + 0.3T) and Y <(X _AVE + T)
Can be set to a value that satisfies.

  The second comparator 334 functioning as a double blank detection unit detects, as a double blank, a case where the slide position signal hold value X is greater than or equal to the abnormality identification value Y set within the range of the above [Equation 2]. .

In this example, the abnormality identification value Y is set on the basis of the average value X _AVE of the slide position signal hold value X as shown in [Expression 2]. The abnormality identification value Y may be set on the basis of the slide position signal hold value obtained when trials of the stacked blank material.

That is, assuming that the slide position signal hold value obtained when trying the two-layered blank material is X ′ and the thickness of the blank material is T, the abnormality identification value Y is as follows:
[Equation 3]
Y <X ′ and Y ≧ (X′−0.7T)
Can be set to a value that satisfies.

Since the slide position signal hold value X ′ obtained when two blank sheets are tried is larger than the average value X _AVE of the slide position signal hold value X by one sheet thickness of the blank material, ] And [Expression 3] show substantially the same range.

  The second comparator 334 detects the slide position signal hold value X as a double blank when the slide position signal hold value X is equal to or greater than the abnormality identification value Y set by the above [Equation 2] or [Equation 3]. A command for suddenly braking the slide 110 can be output to the device 305, and “double blank detection” can be notified on the die protection device setting screen of the die cushion operating device.

[Safety treatment device]
When the double blank detection device 302 detects a double blank, the safety treatment device 305 shown in FIG. 12 outputs a command for suddenly braking the slide 110 to the press controller 190.

  In response to this command, the press controller 190 outputs a torque command signal 197 in the slide reaction direction to the press drive device 240 to start sudden braking of the slide 110. In addition, after the slide 110 stops (almost at the same time as the stop), the press controller 190 turns off the brake release electromagnetic valve 235 of the brake device 230 and applies the brake.

  In addition, when the double blank detection device 302 detects a double blank, the safety treatment device 305 simultaneously sends a command for suddenly braking the slide 110 and, at the same time, the hydraulic cylinders 107R and 107L in the head-side hydraulic chamber 109 built in the slide 110. Is output to the overload removal device 220 via the selector 198.

  In response to this command, the overload removal device 220 (FIG. 10) turns on the electromagnetic (relief) valve 228 and moves the head side hydraulic chamber 109 of the hydraulic cylinders 107R and 107L via the electromagnetic (relief) valve 228. Connected to the low-pressure accumulator 223, the head side hydraulic chamber 109 is depressurized.

  Further, when the double blank detection device 302 detects a double blank, the safety treatment device 305 applies a predetermined amount to the cushion pad 128 in order to abruptly contract the head side hydraulic chamber 109 of the hydraulic cylinders 107R and 107L that have been depressurized. A command for applying a die cushion load (in this example, a maximum capacity of 3000 kN) is output to the pressure controller 134.

  In response to this command, the pressure controller 134 outputs torque command signals 177R and 177L that cause the maximum capacity of 3000 kN to act on the cushion pad 128.

[Operation of double blank detection and safety treatment device]
FIG. 15 is a waveform diagram showing a slide position and a die cushion position, and FIG. 16 is a waveform diagram showing a predetermined value F of a die cushion load signal, a die cushion load command, and a die cushion load.

  FIG. 17 shows the pressure in the head side hydraulic chamber of the hydraulic cylinders 107R and 107L with a built-in slide, and FIG. 18 is a waveform diagram showing the detection of the slide position signal hold value X, the abnormality identification value Y, and the double blank. is there.

  15 to 18 show waveforms for three cycles, and the first cycle and the second cycle function normally. During the die cushion load control process, the die cushion load is about 2050 kN that tends to slightly exceed when the die cushion load control is started with respect to the command of 2000 kN (FIG. 16).

The pressure in the head side hydraulic chambers of the hydraulic cylinders 107R and 107L is increased according to the press load value during molding (when the die cushion load is applied) with respect to the initial pressure of 200 kg / cm ² (FIG. 17).

  The slide position signal hold value X transitions to 195.23 mm and 195.13 mm (FIG. 18). These are held when the die cushion load signal rises to a predetermined value F (F = 200 kN in this example), and the press / slide position is 10 mm with respect to the slide position 200 mm corresponding to the next die cushion standby position. It is unheld at the upper 210 mm position.

  In the third cycle, a double blank is detected. Since the slide position signal hold value X is 196.2 mm and is equal to or greater than the double blank abnormality identification value Y (= 195.60 mm), the double blank is detected by the double blank detection device 302 (FIG. 18).

  The time when the blank holder 124 and the upper die 120 are in contact with each other through the blank material (two sheets) immediately before the double blank detection (the time immediately before the start of the die cushion load control) is in the state of the right half of the press machine shown in FIG. is there. In this state, the non-molding stroke ΔZ from the blank material lower surface to the lower mold 122 (punch) is 15 mm (ΔZ = 15 mm), and the molding is not started unless the slide 110 (lower surface) is further lowered by 15 mm.

  FIG. 19 to FIG. 22 show cycle waveforms in which a part of FIG. 15 to FIG.

  When the double blank is detected by the double blank detection device 302, the safety treatment device 305 instructs the press controller 190 to brake the slide 110 suddenly. In response to this command, the slide (connecting rod point) position depending on the crank angle suddenly stops (FIG. 19).

  However, the slide (connecting rod point) position descends by about 40 mm inertia and stops at 155 mm due to the inertia of the entire movable portion interlocked with the slide 110.

  At the same time, the safety treatment device 305 commands the electromagnetic (depressure) valve 228 via the selector 198 to depressurize the head side hydraulic chambers of the hydraulic cylinders 107R and 107L with built-in slides. In response to this command, the head side hydraulic chamber is suddenly depressurized (FIG. 21). In order to enhance the rapid depressurization action, the solenoid valve 228 is selected to have a large valve opening (flow coefficient) and capable of high-speed response. Further, in order to enhance the response, the applied voltage at the time of starting ON (excitation) is instantaneously increased (improved to advance the phase of the substantially first-order lag characteristic associated with the electromagnetic force action of the solenoid valve).

At the same time, the safety treatment device 305 instructs the pressure controller 134 to apply the die cushion load command to the maximum capacity of 3000 kN in order to rapidly contract the depressurized head side hydraulic chamber. In response to this command, the die cushion load command immediately changes to 3000 kN (broken line in FIG. 20). The pressure in the head side hydraulic chamber of the hydraulic cylinder with a built-in slide drops to about 20 kg / cm ² when the slide (connecting rod point) position reaches about 185 mm after about 30 ms (around 14.225 s in FIG. 21). ).

  Thereafter, the hydraulic cylinders 107R and 107L start to contract, the slide (lower surface) mold mounting position associated therewith also reverses (turns upward), and a portion including the mold mounting surface of the slide is relatively in the upward direction. Move (broken line in FIG. 19). At this time, the die cushion load is temporarily stabilized to about 2000 kN, which is smaller than the command 3000 kN, under the influence of a decrease in the speed of the slide lower surface that pushes the die cushion (FIG. 20). At this time, the hydraulic cylinders 107R and 107L are indirectly pressed from below by the die cushion load, and continue to contract while discharging the hydraulic oil.

About 25 kg / cm ^{2 corresponding} to the pressure loss generated when the amount of discharged oil flows through the electromagnetic valve 228 acts on the head side hydraulic chambers of the hydraulic cylinders 107R and 107L. In the vicinity of 14.3 to 14.4 s shown in FIG. 21, the hydraulic cylinders 107R and 107L reach the contraction (machine) limit, the amount of discharged oil disappears, and the pressure in the head side hydraulic chamber drops to almost zero. Further, since the speed of the slide lower surface becomes equal to the predetermined slide speed, the die cushion load changes to 3000 kN as instructed (FIG. 20). At this stage, the slide (the connecting rod point position) still continues to move down slightly (FIG. 19), and the die cushion ends the load control (FIG. 20).

  With this series of operations, the minimum position of the slide (lower surface) mold mounting position is about 185 mm (around 14.26 s and 15 s in FIG. 19), which corresponds to the state of the left half of the press machine shown in FIG. . The state of the left half of the press machine shown in FIG. 7 shows just before the blank material comes into contact with the lower mold 122 (punch) and molding starts, and the double blank is detected by this mold protection function. If it is done, the machine is safely stopped in advance (before molding).

  In this way, the hydraulic cylinders 107R and 107L are abruptly contracted only when the position of the lower surface of the slide in consideration of the contraction of the hydraulic cylinders 107R and 107L is in a region where molding is not started. Maximum die cushion load is applied. The die cushion load is basically not applied in the molding region at the time of double blank detection, which is a very dangerous state for the mold with a double blank.

  In the molding area, for example, when the light safety device is shielded from light, when an emergency stop of the press machine during operation occurs, a wrinkle will occur and damage the mold until the press / slide stops. In order to suppress this, the countermeasure is different from the situation where a predetermined die cushion load is applied.

[Others]
In this embodiment, the mold protection device 300 including the double blank detection device 302 and the safety treatment device 305 is built in the die cushion controller 170, but the present invention is not limited to this, and the die cushion control is performed. It may be provided outside the container 170.

  Further, the present invention may be provided with only a double blank detection device, and in this case, a device other than the safety treatment device of the present embodiment may be applied as a safety treatment device at the time of double blank detection. . In addition, it cannot be overemphasized that the double blank detection apparatus which concerns on this invention can also detect the state in which the 3 or more blank material overlapped.

  In addition, when a double blank is detected by the double blank detection device 302, it is preferable to immediately stop the conveying device that sets the blank material on the press machine 100.

  Furthermore, in this embodiment, the cushion pad is supported by two hydraulic cylinders, but the number of hydraulic cylinders is not limited to two, and may be one or more. In addition, the die cushion drive unit is not limited to one using a hydraulic cylinder, but may be any unit that supports the cushion pad, raises and lowers the cushion pad, and generates a desired die cushion load on the cushion pad. Good.

  The hydraulic cylinder with a built-in slide uses oil as the working fluid, but is not limited thereto, and it goes without saying that a hydraulic cylinder using water or other liquid can be used in the present invention.

  Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

10 Crown 20 Bed 80 Material 100 Press machine 101 Reduction gear 102 Bolster 103 Connecting rod 104 Column 105 Piston 106, 150 Servo motor 107L, 107R Hydraulic cylinder 108 Sliding member 109 Head side hydraulic chamber 110 Slide 111 Balancer cylinder 112 Crankshaft 113 Signal converter 114, 115 Encoder 120 Upper mold 122 Lower mold 124 Blank holder 126 Cushion pin 128 Cushion pads 130L, 130R Hydraulic cylinder 130a Rod side hydraulic chamber 130b Head side hydraulic chamber 132 Pressure detector 133L, 133R Die cushion position detector 134 Pressure controller 136 Position controller 138, 198 Selector 140 Hydraulic pump / motor 152 Encoder 153, 194 Signal converter 160L, 160R Die cushion driving device 162, 223 Accumulator 164, 225, 226 Relief valve 166, 224 Check valve 170 Die cushion controller 171L, 171R Die cushion pressure signal 172, 192 Servo amplifier 173L, 173R Die cushion position signal 174 AC power source 175L, 175R Servo motor angular speed signal 176, 196 DC power supply 177L, 177R Torque command signal 190 Press controller 191 Crank angle signal 193 Crank angular speed signal 195 Servo motor angular speed signal 197 Torque command signal 200 Die cushion device 202 Air cylinder 204 Air tank 220 Overload removal Device 221 Induction motor 222 Hydraulic pump 227 Pressure detector 228 Electromagnetic (de-pressure) valve 229 Contactor 230 Brake device 231 Air pressure source 233 Pressure reducing valve 235 Brake release solenoid valve 237 Silencer 239 Brake mechanism 240 Press drive device 300 Mold protection device 301 Die cushion load signal 302 Double blank detection device 303 Slide position signal 305 Safety treatment device 310 Load signal acquisition unit 320 Position signal acquisition Unit 330 double blank detector 331 predetermined value setter 332 first comparator 333 hold circuit 334 second comparator 335 abnormality identification value setter

In the double blank detection device according to still another aspect of the present invention, the abnormality identification value is Y, the average value of the slide position signal hold value obtained by repeating the molding of one blank material a plurality of times is X _AVE , When the thickness of the blank material is T, the abnormality identification value Y is as follows:
Y ≧ (X _AVE + 0.3T) and Y <(X _AVE + T)
Is preferably set to a value that satisfies the above.

The abnormality identification value Y set by the abnormality identification value setting unit 335 is a value obtained by adding half of the plate thickness (0.8 mm) to the average value X _AVE = 195.20 mm of the slide position signal hold value X. It is set (Y = X _AVE +0.5 T = 195.20 + 0.5 × 0.8 = 195.60, where the plate thickness is T).

Claims (13)

In a double blank detection device of a press machine that uses a press machine with a die cushion device to automatically and repeatedly form blank materials one by one,
A position signal acquisition unit for acquiring a slide position signal indicating the position of the slide of the press machine;
A load signal acquisition unit for acquiring a die cushion load signal indicating a die cushion load generated in a cushion pad of the die cushion device;
A double blank detection unit for detecting, as a double blank, a state in which a plurality of the blank materials overlap based on the slide position signal acquired by the position signal acquisition unit and the die cushion load signal acquired by the load signal acquisition unit;
Double blank detection device for press machines equipped with   The double blank detection unit holds the slide position signal when the die cushion load signal rises to a predetermined value, compares the held slide position signal hold value with an abnormality identification value, and holds the held slide position. The double blank detection device for a press machine according to claim 1, wherein a case where a signal hold value is equal to or greater than the abnormality identification value is detected as the double blank. Assuming that the abnormality identification value is Y and the average value of the slide position signal hold value obtained by repeating the molding of one blank material a plurality of times is X _AVE and the thickness of the blank material is T, the abnormality identification value Y Is the following condition,
Y ≧ (X _AVE + 0.3T) and Y <(X _AVE + T)
The double blank detection device for a press machine according to claim 2, wherein the value is set to a value satisfying. Assuming that the abnormality identification value is Y, the slide position signal hold value obtained when two blank sheets are tried is X ′, and the thickness of the blank material is T, the abnormality identification value Y is as follows: conditions,
Y <X ′ and Y ≧ (X′−0.7T)
The double blank detection device for a press machine according to claim 2, wherein the value is set to a value satisfying.   5. The press machine double blank detection according to claim 2, further comprising: a first manual setting device that manually sets the abnormality identification value, or a first automatic setting device that automatically sets the abnormality identification value. 6. apparatus.   The press machine double according to any one of claims 2 to 5, wherein the predetermined value of the die cushion load signal is a value within a range of 5% to 20% of a maximum die cushion load of the die cushion device. Blank detector.   7. A second manual setting device for manually setting a predetermined value of the die cushion load signal, or a second automatic setting device for automatically calculating and setting based on a maximum die cushion load of the die cushion device. A double blank detection device for a press machine as described in 1. A slide position detector for detecting a slide position of the press machine and outputting the slide position signal, and a die cushion load detector for detecting a die cushion load generated on the cushion pad and outputting the die cushion load signal And comprising
The position signal acquisition unit acquires the slide position signal from the slide position detector,
The double blank detection device for a press machine according to any one of claims 1 to 7, wherein the load signal acquisition unit acquires the die cushion load signal from the die cushion load detector. A braking device that brakes a slide driven by a press driving device of the press machine, and a mold mounting surface of the slide relative to the movement of the slide that is built in the slide and driven by the press driving device. A hydraulic cylinder to be moved to the press machine,
A double blank detection device for a press machine according to any one of claims 1 to 8,
When the double blank is detected by the double blank detector, the braking device starts sudden braking of the slide, and the hydraulic cylinder is depressurized to raise a part including the mold mounting surface of the slide. A safety treatment device that moves relative to the direction;
Mold protector for press machine equipped with. The die cushion device is:
A die cushion driving unit that supports the cushion pad, raises and lowers the cushion pad, and generates a die cushion load on the cushion pad;
A die cushion load commander that outputs a die cushion load command;
A die cushion load controller that controls the die cushion drive unit based on a die cushion load command output from the die cushion load commander and generates a die cushion load corresponding to the die cushion load command on the cushion pad; With
When the double blank is detected by the double blank detection unit, the die cushion load commanding device is a predetermined period of time until the slide stops only in a region in which molding of the cushion pad does not start. The die cylinder load command is output, the hydraulic cylinder is degenerated by the die cushion load generated in the cushion pad in response to the die cushion load command, and a part including the mold mounting surface of the slide is moved upward. The mold protecting device for a press machine according to claim 9, wherein the mold protecting device is moved relatively. The die cushion device is:
A die cushion position commander that outputs a die cushion position command;
After the die cushion load control by the die cushion load controller is completed, the die cushion driving unit is controlled based on a die cushion position command output from the die cushion position commander, and the cushion pad is raised to increase a predetermined die cushion. A die cushion position controller for moving to a standby position,
The die protection device for a press machine according to claim 10, wherein the predetermined die cushion standby position is a position moved in a rising direction by a predetermined amount from a position at which molding is started.   The die protection device for a press machine according to claim 11, wherein the region where the molding is not started is a region between the predetermined die cushion standby position and a position where the molding is started.   The die cushion load command device automatically outputs a maximum die cushion load command as the predetermined die cushion load command when the double blank detection unit detects the double blank. 2. A mold protection device for a press machine according to item 1.

Images